The Scientist Who Loves To Push
Most Advanced Computers To Their Limit

Sonia Chopra

When the National Aeronautics and Space Administration purchased a massive
parallel computer some years ago, they looked for scientists who could
advise them on its use for basic research.

One of the few experts that NASA called upon nationwide was Tara Prasad
Das,
professor of physics at the State University of Albany. Although, Das was
not
a computer scientist, he was ideal for NASA's task because he, along with
his
research group, has extensive experience performing calculations that can
challenge the most advanced computers.

By performing their vast computations on both traditional computers and
NASA's new machine, Das and his assistants have been able to provide an
important basis for comparison between the two computing systems.

"It is important to know how something works, but it is more important to
know why. Finding out the 'why' is basic research; the 'how' is technology.
If you know more 'whys,' you will produce a lot more 'hows,' said
66-year-old
Das, in an interview last week.

Das is a computational theoretical physicist who routinely drives the most
powerful computers to their limits. Why? Because he uses these computers as
a
tool in solving complex mathematical equations that describe the inner
workings of atoms and molecules.

Most of us have learned an elementary approximation of what occurs in atoms
of high school physics. We were taught to think of the atom as a tiny solar
system with the nucleus, containing protons and neurons, as the sun and the
electrons, like planets, orbiting the nucleus.

This planetary model may be a neat and structured way for ordinary mortals
to
conceive of atoms but it's highly misleading. In fact, in an atom, the
forces
between the electrons make a shambles of neat and orderly orbits. Unlike
planets in the solar system, which orbit in the same planes, electrons in
the
atom orbit in countless planes. As atoms bind together from molecules, they
share electrons.

This actually gets a bit complicated for a few minutes more -- electrons
have
a tendency to act like waves. These wavelike characteristics require
quantum
mechanics for their description -- and the nucleus also acts like a magnet --
the magnetism or so-called magnetic moment, of the nucleus is caused by the
spinning of protons and neutrons insides the nucleus.

The magnetic field caused by the orbiting electrons interacts with the
magnetism of the nucleus of the atoms. This interaction, known as hyperfine
interaction is what Das has spent his career studying.

"You can figure what precisely what electrons are doing in atoms by
studying
these hyperfine fields," said Das, adding that by using complex
mathematical
equations to represent the motions of electrons in atoms and other systems,
he calculates electron distribution and then tests his solutions against
the
data obtained by the experimental physicists.

One of the projects that Das and other physicists have improved the
scientists' knowledge of the electronic structure of hemoglobin since 1967.
Their study deals with cooperativity in hemoglobin, which refers to the
fact
that as soon as one of the hemoglobin's protein chains attaches to oxygen,
it
prompts the second protein to get hungry for oxygen and so on and so
forth.

It would be natural to expect a man who spends his time wrapped up in
mathematical theory and computer calculations to be eccentric, distant,
distracted and very difficult to comprehend or communicate with but that's
not the case with Das.

Charming, gracious, almost apologetic, Das sometimes broke into his native
Bengali with this reporter knowing that she has been born and brought up in
Calcutta, where the I-don't-care-what-the-official-language-is-we
speak-Bengali attitude rules.

He was excited and animated in his discussions of physics, which he
liberally
sprinkles with his observations on philosophy and religion, which are drawn
largely from his upbringing in India.

On his curiosity with electrons, structures and other scientific stuff, Das
said, "God sends us into the world. We can just live and not ask questions.
But if we can follow up our observations and find out a little bit more
about
how something works, then we can get a better understanding about the
relationship between ourselves and the divine."

Das earned his PhD in 1955 from Calcutta University's Saha Institute of
Nuclear Physics. He joined the Chemistry Department at Cornell University
for
a year, where his immediate interest as a post-doctoral scientist was the
newly discovered field of nuclear magnetic resonance, which today is a
vital
part of medical scanning technology used in hospitals to provide
noninvasive
pictures of the interior of the body.

For him, though, the interest was purely in understanding the theory of
nuclear magnetic resonance better. "What fascinated me at that time was,
what
can you learn from this new toy," he said.

This led him to co-author the book Nuclear Induction, published by the
Saha
Institute -- this book is still used today. His interest in hyperfine
interactions have continued since then.

Das then joined the Physics Department at the University of California,
Berkeley, where he collaborated on a second book on a technique closely
related to NMR. The book Nuclear Quadruple Resonance Spectroscopy
published
by Academic Press is also still in use, 30 years later.

Then he came to SUNY Albany.

In 1973, Das also wrote a textbook, Relativistic Quantum Mechanics of
Electrons, published by Harper & Row. Das has published 251 papers and nine
review articles. He attributes his extraordinary productivity to his
"excellent graduate students, post-doctoral associates and experimental
colleagues."

Das has guided 50 graduate students through their PhDs and he is
supervising
the research of seven doctoral candidates. He working on papers with
scientists in West Germany, Sweden, The Netherlands, Belgium, Japan and
India
and has been invited to international conferences to present papers almost
every few months.

Examples of these are the International Conference on Hyperfine
Interactions
held last August in Dublin.

Then in October, Das was invited at the Institute of Physical and Chemical
Research in Wako-Shi, Japan to lecture on fusion techniques for energy
production. From there, he went to Bangalore for the meeting of the
International Union of Materials Research Societies, where he presented a
review of the current understanding of ferromagnetism in solid state
systems.
In January, he traveled to the University of Zurich in Switzerland to
discuss
the understanding of magnetic and hyperfine products.

His wife, Basanta Manjori Das, sometimes accompanies Das; they live in
Guilderland, a few miles north of Albany.

Industry has also drawn on Das's talents. He has had numerous associations,
either as a visiting scientist or consultant at the industrial research
laboratories of GTE, IBM, RCA, Gulf General Dynamics and the Xerox
Corporation.

Das collaborates with numerous other experimenters, as well. Worldwide, the
physicist provides theoretical support for the work of several atomic and
molecular and solid state physicists. There is only a handful of physicists
worldwide who do the work Das does.

Das offers a favorite anecdote, one he often uses in the classroom, to
explain why it is so important for experimental and theoretical physicists
to
interact closely.

"There were once three blind men who met an elephant. They weren't sure
what
it was they had encountered," he said. "One of them touched the elephant's
tusk and said, `it is something hard.' Another touched the leg and said,
`It
is like a pillar.' The third touched the elephant's ears and thought he was
touching a fan. But it was only when the three of them put their
observations
together that they came up with a total picture."